In recent years, the manipulation of radiographic cassettes in daylight has undergone a real breakthrough in that apparatus have been devised and marketed which enable radiographic cassettes to be loaded and unloaded in daylight conditions. A key-element in some of such radiographic systems is a so-called intermediate unloader and associated storage facility by means of which exposed radiographic film sheets are unloaded from cassettes and temporarily stored preparatory to being fed into a radiographic film processing apparatus. Such an intermediate facility is useful e.g. in medical radiographic departments in which a series of sequential examinations of one or more patients needs often to be performed. The individual exposures are sequentially delivered to the storage facility which comprises a removable magazine. The storage magazine is subsequently transferred, in light-tight closed condition, from the loader to an unloader associated with a processing apparatus wherein the films unloaded from the intermediate storage magazine are processed in the same sequence.
Some of the prior art intermediate storage facilities are of the type comprising a so-called roller-magazine comprising a light-tight housing which has a screenable slot through which the exposed film sheets enter the housing from the cassette unloader and which contains a film-guiding web having its ends connected to rotatable cores. Film sheets entering the housing become positioned upon this web and are carried along thereby as it is wound from one core to the other. Consequently the films become sandwiched between adjacent convolutions of the web. When the film sheets are to be dispensed from the magazine to a processing apparatus the direction of rotation of the cores is reversed and films are delivered from the entrance slot of the magazine towards transporting rollers at the inlet of the processing apparatus.
It will be evident that such roller-type magazines suffer from the disadvantage that the film sheets are delivered from the magazine in the reversed order from that in which they were fed into it. For some radiographic techniques in which e.g. use is made of contrast enhancing fluids (for example in the gastro-intestinal field) or when motion studies are carried out, the preservation of the correct sequence may be of great importance.
Another type of intermediate unloader is disclosed in our U.S. Pat. No. 4,338,522 issued July 6, 1982 in which a radiographic cassette unloader is disclosed having twin storage magazines. One magazine receives exposed film sheets from the unloader and the other magazine is coupled to a dispenser from which exposed film sheets are dispensed one by one for processing. The interiors of the two magazines are separated by walls which are displaceable to enable film sheets accumulated in the first magazine to be transferred to the second and after such transfer these walls can be closed to enable feeding of sheets into the first magazine and dispensing of sheets from the second to continue simultaneously. The first magazine can be removed from the unloader and taken to a different sheet dispensing site but the magazine when removed is not light-tight and the transfer cannot be effected in daylight.
Also, due to the manipulation to be carried out, mistakes of human nature cannot be fully excluded and the coupling stage itself is rather complicated.